Quartz crystals are typically employed as frequency sources in electronic systems due to their outstanding performance characteristics such as excellent accuracy, stability, phase noise, and aging characteristics. Crystals are also quite inexpensive but are relatively large in size. Semiconductor-based solutions, such as phase-locked loops, may also be employed for frequency generation. Phase-locked loop based clock sources offer some advantages over crystals such as faster turn-on, smaller size, and lower cost. Moreover, phase-locked loop based clock sources can operate in a spread-spectrum mode to reduce noise generation. However, compared to crystals, phase-locked loops consume much more power and in some cases may introduce unacceptable levels of phase noise and/or jitter. Typical implementations of other semiconductor-based solutions such as electronic oscillators in many cases also generate unacceptable levels of phase noise. Consequently, crystals have remained prevalent as frequency sources in electronic systems.
Existing electronic systems typically include a plurality of crystals from which to generate required system frequencies under various operating conditions. For example, devices such as media players, digital cameras, cell phones, PDAs, etc., typically include 2-5 crystal based frequency sources; and a notebook computer typically includes as many as nine crystal based frequency sources. An electronic system typically includes at least one low frequency crystal. For example, most systems include a 32.768 kHz crystal since this frequency has become the de facto standard time base for real time calendar and clock circuitry, which is commonly found in most electronic devices. Moreover, most systems also include one or more high frequency crystals, e.g., to generate frequencies in the megahertz range. No viable techniques currently exist for eliminating the need for a plurality of crystal frequency sources in electronic systems.